from the observer appears redder, its
movement “stretching” the
wavelength of the light rays. This
elongation is also known as
“redshift.” The faster the object is
moving away, the more pronounced
its redshift. Redshifting is
characteristic of many astronomical
objects, such as galaxies, that are
moving away from us at great speed
because of the primordial explosion,
or Big Bang. 
 Conversely, objects that are moving
toward us are blueshifted, their light
being shifted toward the blue end of
the spectrum.